The latest clash between Israel and the Palestinians is the most serious in years, and it keeps getting worse.

On Monday, dozens of rockets fired from the Gaza Strip landed deep inside Israel. On Tuesday, Israel unleashed an aerial bombardment of Gaza, called up military reservists and said it was considering a ground attack.

The tension is being inflamed by anguish over the kidnapping and murder of three Israeli teenagers last month and the burning to death of a Palestinian teenager in a suspected act of revenge.

"We’re looking at a very difficult game of nerves," said Natan Sachs, a fellow in the Saban Center for Middle East Policy at the Brookings Institution.

What happens next — whether this cycle of violence explodes into a war or dials back down to simmering resentment — depends on variables almost too numerous to quantify, much less predict. The experts see both encouraging signs and a few reasons to worry.

REASONS TO HOPE

Palestinian view

The objectives of Hamas, the militant Palestinian group that controls Gaza, aren't fully clear, although it said Tuesday that it wants Israel to free prisoners detained in the West Bank last month. But the larger Palestinian public is not invested in a major conflict, said Aaron David Miller, a Middle East scholar at the Wilson Center, a nonprofit policy research organization.

At least until recent months, Israel and the Palestinian Authority were characterizing their cooperation on security matters as perhaps the strongest it's ever been.

The single most important thing that Palestinian President Mahmoud Abbas could do now, Miller said, is come up with information leading to the arrest of the people responsible for kidnapping and killing the Israeli teens. Israel is conducting a manhunt for two Hamas-affiliated Palestinians in the West Bank whom it believes were responsible.

In the meantime, violence will likely continue in Gaza, Miller said, but he doesn't believe it’s close to spinning out of control.

Netanyahu’s restraint

Benjamin Netanyahu, the Israeli prime minister, told his country on Tuesday to prepare for a long operation against Hamas. He encouraged Israelis "to be strong and united, since it might take time."

But he is not quick to war. Despite being the second-longest-serving man to hold the job, he's executed only one major military operation, Sachs noted. That was a November 2012 campaign against Hamas in Gaza called Pillar of Defense. And even that didn't involve ground troops.

"Of course, he may yet use ground troops — in a limited way — this time," Sachs said.

The rest of the Middle East is aflame

Sounds counterintuitive, but it could help. Palestinians and Israelis don’t want the same kind of meltdown they see nearby in Iraq and Syria, Miller said.

Israel looks at the Middle East and sees "a situation that Israel can't control," Sachs added. He said Israel is jittery and wants to stop the Hamas rocket attacks, but it is not consumed by the worry that it will be engulfed. If Hamas stops the rockets, Israel will be inclined to reciprocate with calm, Sachs said.

REASONS TO WORRY

It's not just Gaza

The trouble is not limited to the Gaza Strip. The three Israeli teenagers and the Palestinian teenager were all killed in the disputed West Bank, and clashes between Palestinians and Israeli police broke out in Jerusalem after the Palestinian teen was buried.

All across the region, "if we get something from left field, another kidnapping, this could get worse," said Jean-Marc R. Oppenheim, an adjunct associate professor in Middle East studies at Fordham University. “This is bad. It’s not nearly as bad as it might be.”

Egypt has its hands full

In the past, Egypt has been peacemaker. It negotiated the cease-fire that ended the last similar major of violence across the Israel-Gaza border, in November 2012. Egypt shares a border with Gaza and wants to keep it calm.

The problem is that Egypt is a little busy right now. It is looking inward, trying to fix a bad economy, and it has Islamist insurgents to deal with on the Sinai Peninsula. Hamas is allied with the Muslim Brotherhood, and the new people in charge in Cairo consider the Brotherhood a terror group.

Egypt could be motivated to say, "We tried. We can’t deal with it. This is Hamas’s problem," Sachs said. "They may say, you know, you made your bed, now deal with the consequences."

U.S. credibility

There is a sense in the Arab world that the United States is "less credibly threatening" — less interested in getting heavily involved in the Middle East after more than a decade of war in Afghanistan and Iraq, Sachs said.

And a nine-month push by Secretary of State John Kerry for Israeli-Palestinian peace collapsed in April, when Palestinian President Mahmoud Abbas infuriated Israel by agreeing to form a unity government with Hamas.